1. Field of the Invention
The invention is related to an ultrasound system having the real-time monitored apparatus and the method thereof, particularly to a high-intensity focused ultrasound thermal ablation apparatus having integrated temperature estimation and elastography for thermal lesion determination and the method thereof.
2. Description of the Prior Art
In recent years, the noninvasive method has been paid more attention in the clinical medical therapy. The ultrasound thermal therapy is gradually matured. The ultrasound has very good penetrating property in human tissue, which is able to transport the energy to deep tissue, thus it can be widely applied in the noninvasive method, such as the tissue lesion to repress the cancer cells, and the suppression of tumor cells etc. The high-intensity focused ultrasound therapy (HIFU) is a kind of ultrasound thermal therapy technique, basically using the high-intensity focused thermal ultrasound to concentrate the energy of the ultrasound. After the energy of ultrasound is focused, the temperature of tissue at the focus region is suddenly raised to above 70° C. The protein of the cell will be denatured at this temperature, thus the tumor can be burnt. Then, the ill tissue will be killed in order to achieve the goal of killing cancer cells.
In the ultrasound thermal therapy process, in order to control the heating degree to avoid injuring the normal tissue around the cell and effectively understand the dimension and the relevant position of thermal lesion after heating, assess the temperature change at large area and lesion range after heating, a monitoring system becomes very important. If the “thermal therapy” is carried out under a situation without any monitoring system, the clinical physician will be unable to judge the heating position and temperature change inside the tissue accurately. It will also be unable to identify the thermal lesion of tissue after heating. Thus the danger degree of the therapeutical process will be increased, and the application of thermal therapy will be limited clinically.
In the monitoring system of ultrasound thermal therapy technique at present, there both are the “ultrasound temperature imaging technique” and the “elastography technique”.
Wherein, the “ultrasound temperature imaging technique” uses the ultrasound image in the approximate linear range as the shift quantity to estimate the temperature change. However, if the temperature difference is too high and the object is deformed, it will be unable to estimate the position of thermal lesion correctly. When the thermal expansion is occurred in the tissue, and when the relationship between sound speed and temperature is nonlinear, it will also be unable to estimate temperature change accurately. The echo time displacement tracking way can be used to obtain the dynamic and real-time temperature change in the high-intensity focused ultrasound therapy. However, the limiting condition is that the temperature cannot exceed the linear region of sound speed and temperature (below 50° C.). When the temperature exceeds the critical region, the accuracy of temperature estimate will be lost, due to the change of physical properties, such as permanent tissue destruction, thermal sound lens effect etc.
The “elastography technique” uses the compression or vibration of tissue to estimate the elastic property inside the tissue, but higher noise may be produced around the tissue. Due to the “elastography technique” has high sensitivity for the elastic change of tissue, thus the technique is very suitable to label the real necrotic tissue region after burning. However, limited to poorer anti-noise ability of “elastography technique”, the elastic change of necrotic tissue only being contrasted under the necrotic tissue condition has been confirmed. The position and dimension of thermal lesion can only be estimated when the hardness difference is more significant. Unlike the ultrasound temperature imaging technique, it does not have the continuous monitoring ability in the whole therapy process.
Therefore, in order to raise the efficiency of temperature measurement and elastic measurement, it is necessary to develop innovative ultrasound technique, in order to reduce the research and development time and relevant manufacturing cost.